Demand for high-quality raw silk has been increasing greatly in Japan in recent years. The material is produced in specially bred races of silkworm, by reeling off the cocoon. The raw silk production process consists of four main stages : drying and cooking the cocoon, reeling, and bandling. Drying and cooking are the most important stages in the entire process. The quality of the cocoon filament and raw silk and subsequent stages in the process are directly affected by the quality of the drying step. Moreover, a very costly machine is required for cocoon drying. In these studies, a new filature process based on ethylene oxide gas (EOG), which is used to sterilize microorganisms, was investigated as an alternative to cocoon drying. 1. Effects of EOG : (1) Pupae in the cocoons were dead within 15-20 minutes of applying EOG.(2) Functional paralysis of pupal tissue was suggested as the cause of death by EOG.(3) Fresh raw cocoon could be kept for long periods under natural ventilation. 2. Certification of raw silk treated with EOG : (1) High-quality fresh silk was obtained in slow-speed reeling at 90 C.The cocoon quality was 86% in reelability, 3.0 denier in size and 1.167m in cocoon filament length. 3. Trial production of gas-paks and containers for EOG application : (1) Gaspaks made of polyethylene film and containers constructed from aluminum alloy were manufactured, for convenience and simplicity. (2) 100g of EOG per container was sufficient for the treatment of 30kg of fresh raw cocoons, at a cost of about 28 yens per treatment.1, EOGと殺蛹機構: 1)殺蛹には15-20分(室温)を要した 2)繭層を通過したEOGは、蛹気門より生体内組織に侵襲し組織呼吸の中枢マヒにて致死を誘起すると判断した 3)生繭は通風換気下で長期間保存が可能であった。2, EOG処理繭糸と生糸特性: 90C以下の低速繰糸により、解舒率86%,3.04d, 1.167mの上繭げ得られた2)節少なく、強度、伸度、抱合とも乾繭糸と変わらぬ5Aの優等生であった3,殺蛹用のガスパックと簡易型EOG容器の試作:1)簡易・軽便化を背景にガスパックはPETで、またEOG容器はガス充填量を100g/本としてアルミ製で試作した2)本品1本で役割30kgの生繭処理が可能で、その際のEOG消費料は28円と算定された